This publication, WGNE Research activities in Earth system modelling, also commonly referred to as the WGNE Blue Book, is a collection of research articles related to Numerical Experimentation and Climate/Earth System Modelling from around the world. It was collected and put together by the ESMO IPO in collaboration with members of the WGNE panel and support from several WCRP members. Note that the report is not a peer-reviewed journal and also not an official WMO or WCRP publication.